Shitake Mushroom Extract
Also known as: Shiitake mushroom, black forest mushroom, golden oak mushroom, lentinan, eritadenine, Lentinula edodes
Overview
Lentinula edodes, commonly known as Shiitake mushroom, is an edible fungus native to East Asia, widely cultivated for both culinary and medicinal purposes. Extracts are typically derived from its fruiting bodies or mycelium. It is recognized as a functional food supplement, primarily valued for its immunomodulatory and potential anticancer properties. Key bioactive compounds include lentinan (a β-1,3-glucan polysaccharide), eritadenine, and various other polysaccharides. Shiitake is used to modulate the immune system, as an adjunct in cancer therapy, to regulate lipid metabolism, and as an antimicrobial agent. Research into its health benefits is ongoing, with a moderate level of maturity, encompassing extensive preclinical data, several clinical trials, and some meta-analyses, though clinical evidence can be mixed due to study design limitations.
Benefits
Shiitake mushroom extract offers several evidence-based benefits. Its primary effect is immunomodulation; clinical trials show that daily consumption of 5-10g of shiitake for 14 days enhances immune markers such as γδ-T cells, NK cells, and salivary secretory IgA, indicating improved immune function. Elderly subjects, in particular, have shown increased B and NK cell counts after supplementation with purified shiitake β-glucan. Regarding anticancer effects, a 2021 systematic review and meta-analysis of observational studies found mushroom intake, including shiitake, associated with a reduced risk of various cancers, such as breast cancer, with pooled relative risks (RRs) indicating protective effects (RR <1). However, clinical trial results for lentinan as an adjunct in cancer therapy are mixed; a 2002 meta-analysis suggested modest overall survival improvement in advanced gastric cancer (HR 0.8), but more recent RCTs have shown no significant benefit or even shorter survival times. Secondary benefits include improved lipid metabolism, as eritadenine inhibits S-adenosyl homocysteine hydrolase, and antimicrobial properties, with extracts potentially reducing gingivitis and dental plaque by preventing bacterial adhesion.
How it works
Shiitake mushroom exerts its effects primarily through immunostimulation, activating innate immune cells like NK cells and γδ-T cells, and increasing the production of cytokines such as IL-2 and TNF-α. The key bioactive compound, lentinan, a β-glucan, interacts with receptors on immune cells, such as Dectin-1, to trigger these responses. Its antitumor activity is thought to involve the induction of apoptosis in cancer cells via caspase-3 and -8 pathways. Additionally, eritadenine contributes to lipid metabolism regulation by inhibiting S-adenosyl homocysteine hydrolase. While polysaccharides like lentinan are poorly absorbed orally, their immunomodulatory effects are likely mediated via interaction with gut-associated lymphoid tissue, leading to indirect systemic immune activation.
Side effects
Shiitake mushroom extract is generally well tolerated with a low incidence of adverse effects. Common side effects, reported in over 5% of users, include mild gastrointestinal discomfort. Uncommon side effects, occurring in 1-5% of individuals, may involve allergic reactions, particularly in sensitive individuals. Rare side effects, affecting less than 1% of users, have not been significantly reported in high-quality studies. Due to its immune-activating properties, shiitake may potentially interact with immunosuppressant medications, and caution is advised for individuals undergoing such therapies. It is contraindicated for immunocompromised patients or those on immunosuppressive therapy, who should consult healthcare providers before use. While elderly individuals may benefit immunologically, cancer patients should use shiitake under strict medical supervision.
Dosage
For immunomodulatory benefits, a minimum effective dose of 5g/day of whole dried shiitake mushroom or 2.5mg/day of purified β-glucans (e.g., Lentinex®) has been observed. Optimal dosage ranges for general immune support are typically 5-10g/day of dried shiitake mushroom. Lentinan doses used in clinical trials for anticancer adjunct therapy vary and are often administered intravenously or in oral formulations standardized for β-glucan content. The maximum safe dose is not well defined, but animal studies have not shown major toxicity at high doses. To observe immune effects, daily intake for at least two weeks is recommended, with longer durations for potential anticancer adjunct use. Extracts standardized for lentinan or β-glucan content are preferred for consistent effects. Oral bioavailability of polysaccharides is low, with immune effects primarily mediated via the gut immune system. No specific cofactors are identified as required, but general nutritional adequacy supports immune function.
FAQs
Is shiitake extract effective for cancer treatment?
Evidence is mixed. Some meta-analyses suggest modest survival benefits as an adjunct therapy in gastric cancer, but other randomized controlled trials show no significant effect or even worse outcomes. It should only be used under medical supervision for cancer.
Is it safe to take shiitake supplements daily?
Generally, yes, with a low risk of side effects like mild gastrointestinal discomfort. However, if you are immunocompromised or on medications, especially immunosuppressants, consult a healthcare provider before daily use.
How soon do benefits appear?
Immune benefits, such as enhanced immune markers, can appear within two weeks of consistent daily supplementation. Potential anticancer effects, if any, would require much longer-term evaluation and are less certain.
Does cooking destroy active compounds?
Some polysaccharides in shiitake are heat-stable, meaning cooking may not destroy all active compounds. However, the potency and concentration of bioactive compounds can vary significantly depending on extraction methods used for supplements.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8483951/ – This systematic review and meta-analysis of observational studies found a significant association between mushroom intake, including shiitake, and a reduced risk of various cancers, particularly breast cancer. The study suggests a protective effect, but acknowledges the observational nature of the data and potential confounding factors.
- https://www.cancertherapyadvisor.com/factsheets/shiitake-mushroom-lentinan-and-cancer/ – This source discusses the use of lentinan, a shiitake component, as an adjunct in cancer therapy. It highlights a 2002 meta-analysis suggesting modest overall survival benefits in advanced gastric cancer when combined with chemotherapy, but also notes conflicting results from more recent randomized controlled trials that showed no significant benefit or even shorter survival times.
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8401741/ – This review of clinical trials focuses on the immunomodulatory effects of shiitake β-glucans. It reports that supplementation, even for short durations (e.g., 14 days), can significantly enhance immune markers such as γδ-T cells, NK cells, and salivary secretory IgA in healthy adults and elderly individuals, indicating improved immune function.
- https://www.signos.com/blog/shiitake-mushroom-benefits – This article provides a general overview of shiitake mushroom benefits, including its potential role in lipid metabolism and antimicrobial properties. It mentions that eritadenine from shiitake can inhibit S-adenosyl homocysteine hydrolase, which may contribute to improved lipid profiles, and that extracts may reduce gingivitis and dental plaque.
- https://www.mskcc.org/cancer-care/integrative-medicine/herbs/shiitake-mushroom – This resource from Memorial Sloan Kettering Cancer Center provides a comprehensive overview of shiitake mushroom, detailing its bioactive compounds like lentinan and eritadenine, and their proposed mechanisms of action, including immunostimulation, antitumor activity through apoptosis induction, and lipid metabolism regulation.
Supplements Containing Shitake Mushroom Extract
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